Drawing device



Aug. 25, 1959 K. F. HARCHIKOV DRAWING DEVICE 2 Sheets-Sheet 1 Filed Jan. 22, 1958 FIG.2

FIG.4

Aug. 25,1959 K. F. HARCHIKOV DRAWING DEVICE Filed Jan. 22, 1958 2 Sheets-Sheet 2 FIG.5

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United States Patent O 2,900,725 DRAWING DEVICE Konstantin F. Harchikov, Brooklyn, N. Application January 22, 1958, Serial N0. 710,458

3- Claims. ores-41 i This invention relates to drawing devices and more parploy so-called railroad rulers or curves having an edge conforming approximately to such a radius of curvature so that with only slight skill the required are may be drawn without use of a compass. The railroad curved ruler however provides at most, only two working edges, and usually only one edge is convenient touse so that a set of rulers having various degrees of curvature usually are necessary. These rulers, being substantially rigid, even in large sets cannot be used for exacting work except when a single ruler is provided for the desired arc, so that no matter what number of rulers are provided in a set, its usefulness is generally a matter of chance.

An object of the present invention is to provide a railroad ruler accessory which, when used in conjunction 'with only a few such rulers, will enable the facile drafting of curved lines or arcs having great range in radius of curvature and varying from each other by any number of degrees of difference.

Another object of the invention is to provide an accessory of this type which may be employed to draw radial lines when the center of a circle in question is not located or accessible provided the radius of curvature is known.

The attainment of these objects, and others which will be apparent further below, is reached by the invention which, briefly described, includes a substantially flat pencil or pen guiding device having a base portion provided with an arcuate inner edge having, or adjustable to have at least two and preferably three or more, points thereon to engage radially against the outer edge of the railroad ruler with which it is to be used. The portion of the device outer of its inner edge is provided with a small aperture therethrough to serve as a pencil point guide. In operation the device, with pencil or pen point therethrough is sliden, by the use of the pencil or pen along and against the outer edge of the railroad curve, the device holding the pencil point a predetermined fixed distance from the outer edge of the railroad curve.

In the accompanying drawing showing, by way of example, two of many possible embodiments of the invention,

Fig. 1 is a plan of one form of the invention,

Fig. 2 is a longitudinal sectional view of the invention as shown in Fig. 1, the section being taken along the line 22 looking in the direction of the arrows of said line,

Figs. 3 and 4 are transverse sectional views of the invention of Fig. 1 the sections being taken along the lines 3-3 and 4-4 respectively of Fig. 1 looking in the direction of the arrows of said lines,

Fig. 5 shows the use of the device with a railroad curve,

Fig. 6 is a plan of another form of the invention, and

Fig. 7 is a sectional view of the form of the invention shown in Fig. 6 the section being taken along the line 7-7 of Fig. 6 looking in the direction of the arrows of said line.

When variation of radius by minute degrees is desired the form of the invention more preferably is shown in Fig. 1 wherein the device 10 comprises a body 11 of generally inverted T or Y shape, substantially flat and preferably transparent. The material may be a plastic such as is ordinarily used for draftsmens triangles. The body has a transverse base portion 12 and stem portion 14 provided with a longitudinal medial slot 15 extending as near to the lower edge of the base as possible without undue weakening of the device.

A slide block 16 is disposed within the slot 15 and is provided with outstanding flanges 18 with rabbe't grooves 19 in the lower face 20 of the stem portion and on each side of the slot. The block is provided with an upwardly projecting screw 21 fast thereon. A thumb nut 22 on the screw has a lower shoulder 24 engaging with the upper marginal portion 25 on each side of the slot 15 to secure the slide block against movement when desired. The lower face 26 of the block is flush with the face 20 when the block is secured tight in the slot. A small aperture 28 passing through the block in a portion nearest the inner end of the stem accommodates the pencil or pen point.

Preferably, the slot is closed at its inner end by a metal tie piece 29 secured to the base portion as by four ears 30 so that the slotted stem will not be severely weakened and yet permit maximum movement to the inner end of the base, the yoke 31 of the tie piece being quite thin.

The base 12 is provided with symmetrical lateral portions 32 on which are mounted, like are pieces 34, at an end portion of such piece, for pivotal movement substantially in the plane of the body about clamp screws 35 having thumb nuts 36. The lower faces 38 of the arc pieces are coplanar with face 20. Each arc piece is provided with an inner edge 39 which is preferably curved to fit or generally conform to the outer edge of the railroad ruler with which the device is to be used. If, for instance, curves having a radius of curvature greater than two inches and not exceeding say about six inches are to be drawn, the edges 39 are preferably made to lit a two inch ruler. The pivot screws 35 are located symmetrically with respect to the slot 15 and at such a distance from the base end that when the mid point of the tie piece is on the railroad ruler the are pieces can be moved to position so that the edges 39 orbit substantially along and against the two inch railroad ruler 40 as in Fig. 5.

In use, when say an arc of 4 and 7 inch radius. is desired, and a two inch railroad ruler is available, the ruler 40 is disposed along a horizontal line H and the slot alined with a previously drawn vertical line V. The are pieces are then adjusted to position so that their edges abut on the ruler 40 and then clamped. The slide block is set in position so that the hole 28' is 2 and inches from the inner face of the tie piece, and then, with the ruler 40 held fast, the device is moved with the aid of the pencil point, passing through the hole, along an arc to dotted position. Especially when a pen is used it may be better to hold the pen in the slot and have it bear against the upper end 28 of the block. By either use, arcs such as at C can be traced. Hardly any skill is required to drag the device and hold it against the ruler by employing only the end of the pencil or pen.

It is not necessary that the edges 39 conform exactly to the outer edge of the ruler. By shifting the position of the arc pieces a ruler of greater radius of curvature may be used with an appropriate diflferent position of the slide block. The procedure for positioning the are pieces is the same except that the outer extremities of the arc pieces are abuttable, in addition to the tie piece. An indicia scale 41 is provided on the stem to facilitate measurements.

If the same railroad ruler is to be-used forallwork the .arc pieces 34 may be integral with vthe .base 12. Under such conditions-it may be that close adjustment of the slide block position is not required. Under such a set of circumstances, it maybe preferable to alter the shape of the body 11 to form a non-adjustable device 110 in the general shape of a flat regular polygon, for example, as shown, a hexagon, ,having inwardly circular arced sides 139, each torfit the constant ruler. The polygon is provided witha series of spaced'holes 128 along the perpendicular bisectorrof the cord of each arced side at. predetermined positions and with suitable legends. Notches 140. aid in handling the device and may be used as pencil point guides.

Of course the devicetmay be used in the construction of other lines such as spiral arcs, parallel straight lines, and joining curves to straight lines tangentially with the aid of only commonly knownprinciples of geometry.

The invention claimed is:

1. A device for drawing lines in conjunction with the use of a curved ruler and comprising a flat body portion of general T shape having a stem and arms and a longitudinal medial slot-through the -stem, and extending between the arms; a slide block having a hole therethrough to restrain the end of a marking device passing through the block, the latter being slidably disposed in the slot; means to secure selectively the block against sliding movement in the slot; arc pieces pivotally mounted on the arms of the body and having curved edges to engage against the outer edge of the curved ruler with which the device is to be used, and means for clamping the are pieces in;fixed;position relative to the body.

2. A device as claimed in claim 1, said device being substantially symmetrical aboutthe general line of the slot.

3. A device as claimed in claim 1, and a metal tie piece on the end-portionof the'body adjacent the arms to strengthen the body to permit the block to approach closely to the outer edge of the ruler.

References Cited in the file of this patent .UNITED STATES PATENTS 1,863,091 Allred June 14, 1932 1,901,764 Mosca Mar. 14, 1933 2,274,727 Neiss et a1. Mar. 3, 1942 2,542,537 K1emm Feb. 20, 1951 2,676,410 Nelson Apr. 27, 1954 2,786,274 ,Early Mar. 26, 1957 

